Protein denaturation.

"Lars Carlsson" <018-422429 at telia.com> wrote:
>Frank wrote:
>"Frank Fuerst" <ffrank at rz.uni-potsdam.de> wrote in message news:9805ai$qus0f$5 at fu-berlin.de...>> "andrzej f. lyskowski" <jendrekl at poczta.onet.pl> wrote:
>>>> Denaturation:
>> - Heat works always,
>> - cold works sometimes
>> - urea or guanidinium chloride are common chemical denaturants.
>>>> How they work? Nobody really knows, at least for the chemicals. They
>> do.
>>>> Bye, Frank
>>>>Urea and guanidinium chloride works by replacing the hydrogen bonds from water and the polypeptide chain itself!
That is what *you* think or argue. Other people have different
opinions. In the end, there may be a mainstream, but there is no
consensus (or near-consensus) in the scientific community.
e.g. nobody really knows exact values for hydrogen bonding energies in
all these cases, and your model depends on the assumption that
hydrogen bonds between protein and denaturant are more favorable than
internal protein h-bonds (because hydrogen bond donors and acceptors
are saturated in folded proteins, so the number of h-bonds cannot be
higher). And this favorable energy has to be big enough to
counterbalance the stabilization by the hydrophobic effect or other
forces.
It seems to me that you are right in that most people think, that the
denaturant mainly acts on the backbone, not on side chains - but this
is, I suppose, also just "common belief" and not proven in any way.
Bye, Frank